A method process of this type is known for a three-phase alternating-current motor, i.e., a three-phase current motor. In this case, the sinusoidal ac supply voltage is rectified into a smoothed dc voltage and is directed--in the form of a supply voltage, to a bridge circuit output stage, consisting of two controllable power semiconductors. The power semiconductors are driven by a driver circuit in such a way that a square-wave ac voltage is produced from the supply dc voltage, wherein the pulse width of the square pulses of this square-wave ac voltage undergoes a pulse-width modulation to the extent that the current flow, resulting in the motor coils, receives a nearly sinusoidal shape due to the induction occurring in the motor windings. This means that a sinusoidal motor current is artificially synthesized by the pulse-width modulation of a square-wave voltage. However, in order to obtain the nearly sinusoidal motor current, it is necessary to reverse the polarity of the motor voltage by means of a pulse rate which constantly changes within a current cycle, i.e. the individual pulses of the square-wave ac voltage must possess varying pulse widths, respectively. A speed adjustment is obtained in that the motor voltage undergoes a pulse-width modulation to the extent that the amplitude of the resulting motor current changes. With the known process, this takes place, disadvantageously with a very extensive circuit layout, in particular for the driver circuit. In the known motor, this is realized by means of a very expensive special IC. Furthermore, it is very disadvantageous that the resulting motor current, depending on the number of "synthesis points," deviates more or less strongly from the sinusoidal shape, so that it has--in each case--a strong harmonic distortion factor, which in turn leads to loud motor noise.